Automatic software downloading from a computer network

ABSTRACT

A method and system to automatically locate, download, verify, install, register and display computer software components from a computer network like the Internet or an intranet. The method and system is used to provide dynamic or interactive multimedia components in HTML documents with HTML &lt;OBJECT&gt; tags. The HTML &lt;OBJECT&gt; tags contain parameters including uniform resource locators (URLs) which reference dynamic or interactive multimedia components on remote computers. Network browsers and other applications can obtain computer software components from a computer network like the Internet or an intranet in a uniform, portable, architecture-neutral, robust manner. The computer software components obtained can be used to provide a variety of new multimedia functionality to an application program which is stored on remote computers.

CONTINUING APPLICATION DATA

This application is a continuation of U.S. patent application Ser. No.08/764,040, filed Dec. 12, 1996 now abandoned.

FIELD OF INVENTION

The present invention relates to browsing of information on computernetworks. More particularly, the present invention relates toautomatically downloading, verifying, installing, registering anddisplaying computer software components from computer networks like theInternet or an intranet.

BACKGROUND AND SUMMARY OF THE INVENTION

The Internet is a world-wide network of cooperating computer networks.Connected to the Internet are thousands of individual computers, eachwith a variety of application programs. From a user's point of view,access to the Internet and its services typically are accomplished byinvoking a network application program (e.g., a network browser). Thenetwork application program acts as an interface between the user andthe Internet. Network application programs are typically “client”applications that accept commands from the user and obtain Internet dataand services by sending requests to “server” applications on othercomputers at other locations on the Internet.

There are many types of client network applications known in the artincluding network browsers such as the Internet Explorer® by MicrosoftCorporation of Redmond, Wash., Netscape Navigator™ by NetscapeCommunications of Mountain View, Calif., and Mosaicm™ by National Centerfor Super Computer Applications (NCSA) in Champaign-Urbana, Ill. Thesenetwork browsers send network requests via the File Transfer Protocol(FTP), Simple Mail Transfer Protocol (SMTP), Hyper Text TransferProtocol (HTTP), Gopher document protocol and others. The networkrequests are used to exchange data with computer networks such as theInternet.

HTTP is a protocol used to access data on the World Wide Web. The WorldWide Web is an information service on the Internet containing documentscreated in the Hyper Text Markup Language (HTML). HTML allows embedded“links” to point to other data or documents, which may be found on thelocal computer or other remote Internet host computers. HTML documentlinks may retrieve the data by use of HTTP, FTP, Gopher, or otherInternet application protocols. The Virual Reality Modeling Language(VRML) is also used to create documents for the World Wide Web.Specifically, VRML is typically used to create three-dimensionalgraphical documents.

The bulk of the information on World Wide Web is static andnon-interactive documents created with HTML. These HTML documentscontain text and still images, while a number contain short audio andvideo clips. As the content of information stored on the Internet andWorld Wide Web evolves, it is desirable to insert dynamic multimediacomponents (e.g., animated buttons, scrolling banners, blinking lights,bouncing or spinning objects, high quality music, and full motion video)and interactive multimedia components (e.g., a computer game sent overthe Internet and played against one or more other users, or a remotecomputer) into a HTML document, to make the information more attractiveand interesting to a user browsing the HTML document.

Network browsers currently support a number of dynamic andpseudo-interactive multimedia components directly. However, there are anumber of problems currently associated with using dynamic andpseudo-interactive multimedia components in a HTML document. Thesebrowsers may still require a user to initiate any dynamic multimediainteraction. For example, a user typically must request the dynamicmultimedia interaction by selecting a remote link with input from akeyboard, electronic mouse or other pointing device. Thus, a user cannotbe provided dynamic multimedia automatically without first asking forit. This again prevents a user from fully enjoying dynamic multimediacomponents.

Since the World Wide Web and the Internet currently support a widevariety of information in multiple formats, a typical network browsercannot directly display every possible dynamic multimedia format itencounters. When a network browser encounters a multimedia component ina HTML document the browser is unable to handle directly (e.g., colorimages with a large number of colors, high quality audio, full motionvideo), it is common in the art for the network browser to call a helperapplication (e.g., a help wizard) that can handle the multimediacomponent. The multimedia component is handed off to the helperapplication for processing (e.g., playing the audio, full motion video).The constantly changing nature of information on the Internet and WorldWide Web requires that the network browser be updated constantly withaccess to new helper applications. This is a time consuming process forthe network browser creators, and prevents a user from fully enjoyingnew multimedia components that might be encountered.

Another frequent problem is that a HTML document may contain anon-standard HTML tag that describes a new dynamic multimedia component.Non-standard HTML tags cause users to constantly incorporate new updatesinto their browsers to take advantage of the dynamic multimediadescribed by the non-standard HTML tags. This is also a slow and timeconsuming process and may require an additional helper application aswas described above.

Most network browsers also do not currently support true interactivemultimedia. Most Internet and World Wide Web sites require a user tofill out and submit an electronic form and rely on a Common GatewayInterface (CGI) application, to invoke a remote software application toprovide pseudo-interactive multimedia content (e.g., database access,search engines, protocol gateways). The CGI provides a mechanism forinformation retrieval, processing and formatting within a HTML document.CGI applications are typically written in a programming language orscripting language other than HTML (e.g., C, C++, Perl, UNIX® shelllanguage) and are executed on a remote computer. This remote executionis typically a slow and cumbersome interface process that also requiresinput (e.g., a mouse click) from a user.

In accordance with an illustrative embodiment of the present invention,the problems of handling dynamic and interactive multimedia in a HTMLdocument are overcome. A method and system for automatically locating,downloading, verifying, registering, installing and displaying asoftware component from a remote computer is provided.

The method is used to automatically locate, download, verify, install,register, and display a computer software component obtained from aremote computer. The system includes a software component downloadmodule for locating computer software components with uniform resourcelocators (URLs), registering computer software components in a registrydatabase, and displaying computer software components on a localcomputer. The software component download module also manages othersystem modules. A data download module downloads computer softwarecomponents in an asynchronous manner from one or more remote computers.A code verification module verifies that the downloaded computersoftware components are safe to install on a local computer by verifyinga digital signature and digital certificate sent with the downloadedcomputer software component. A code installation module installs theverified computer software components on the local computer. Thesoftware components are not limited to the display of multimediainformation. Almost any software component can be downloaded, verified,and installed via the described method and system, whether it is anActiveX™ Control, a Netscape™ ONE Plugin, a Java™ class library, amultimedia player, a document viewer, or a custom control or applet forinclusion on a digital form or a digital document.

The method and system are used by applications (e.g., network browsers,network servers) to automatically download and install softwarecomponents from code depositories on computer networks (e.g., theInternet, or local corporate intranets) to provide dynamic and trulyinteractive multimedia to a user. The method and system allow anysoftware component, including dynamic and interactive multimediacomponents, to be described with a standard tag (e.g., the <OBJECT>tag)in a HTML document.

When the <OBJECT>tag is encountered in a HTML document during browsingwith a network browser, the multimedia software components referenced bythe <OBJECT>tag are automatically downloaded and displayed directly on auser's computer. A HTML document can now provide dynamic multimediacontent and true interactivity, in a uniform, portable,architecture-neutral, robust manner using the method and system of thepresent invention.

Network browsers will no longer require frequent updates or helpapplications to provide dynamic and truly interactive multimedia to auser. A user browsing an HTML document can now be provided with dynamicand interactive multimedia automatically and take full advantage of thevariety of multimedia provided on the World Wide Web, the Internet, andother computer networks such as intranets.

In addition, the method and system of the present can also be used byapplications or devices which are not network browsers (e.g. set topboxes for television network computers, satellite receiver boxes,digital personal assistants and wireless personal communicationsdevices) to automatically locate, download, verify, install, registerand display virtuly any type of computer software component on anyremote computer connected to a computer network like the Internet or anintranet. Any application which desires information from a remotecomputer can use the method and system of the present invention bysending the proper parameter information to the appropriate interfacesprovided by the method and system.

The foregoing and other features and advantages of the illustratedembodiment of the present invention will be more readily apparent fromthe following detailed description, which proceeds with reference to theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of a computer system used to implement anillustrative embodiment of the present invention.

FIG. 2 is a block diagram illustrating a network browsing environment.

FIG. 3 is a block diagram illustrating a system for the presentinvention.

FIG. 4 is a flow diagram illustrating a code downloading method for thepresent invention.

FIG. 5 is a flow diagram illustrating a code locating method for thepresent invention.

FIG. 6 is a flow diagram illustrating a network search method for thepresent invention.

FIGS. 7A-7B are a flow diagram illustrating a registration method forthe present invention.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT

Referring to FIG. 1, an operating environment for the preferredembodiment of the present invention is a computer system 10 with acomputer 12 that comprises at least one high speed processing unit (CPU)14, in conjunction with a memory system 16, an input device 18, and anoutput device 20. These elements are interconnected by a bus structure22.

The illustrated CPU 14 is of familiar design and includes an ALU 24 forperforming computations, a collection of registers 26 for temporarystorage of data and instructions, and a control unit 28 for controllingoperation of the system 10. Any of a variety of processors, includingthose from Digital Equipment, Sun Microsystem, MIPS, IBM, Motorola, NEC,Intel, Cyrix, AMD, Nexgen and others are equally preferred for CPU 14.Although shown with one CPU 14, computer system 10 may alternativelyinclude multiple processing units.

The memory system 16 includes main memory 30 and secondary storage 32.Illustrated main memory 30 is high speed random access memory (RAM) andread only memory (ROM). Main memory 30 can include any additional oralternative high speed memory device or memory circuitry. Secondarystorage 32 takes the form of long term storage, such as ROM, optical ormagnetic disks, organic memory or any other volatile or non-volatilemass storage system. Those skilled in the art will recognize that memory16 can comprise a variety and/or combination of alternative components.

The input and output devices 18, 20 are also familiar. The input device18 can comprise a keyboard, mouse, pointing device, audio device (e.g.,a microphone, etc.), or any other device providing input to the computersystem 10. The output device 20 can comprise a display, a printer, anaudio device (e.g., a speaker, etc.), or other device providing outputto the computer system 10. The input/output devices 18, 20 can alsoinclude network connections (e.g., Internet and intranet connections),modems, or other devices used for communications with other computersystems or devices.

As is familiar to those skilled in the art, the computer system 10further includes an operating system and at least one applicationprogram. The operating system is a set of software which controls thecomputer system's operation and the allocation of resources. Theapplication program is a set of software that performs a task desired bythe user, making use of computer resources made available through theoperating system. Both are resident in the illustrated memory system 16.

In accordance with the practices of persons skilled in the art ofcomputer programming, the present invention is described below withreference to acts and symbolic representations of operations that areperformed by computer system 10, unless indicated otherwise. Such actsand operations are sometimes referred to as being computer-executed. Itwill be appreciated that the acts and symbolically representedoperations include the manipulation by the CPU 14 of electrical signalsrepresenting data bits which causes a resulting transformation orreduction of the electrical signal representation, and the maintenanceof data bits at memory locations in memory system 16 to therebyreconfigure or otherwise alter the computer system's operation, as wellas other processing of signals. The memory locations where data bits aremaintained are physical locations that have particular electrical,magnetic, optical, or organic properties corresponding to the data bits.

The data bits may also be maintained on a computer readable mediumincluding magnetic disks, and any other volatile or non-volatile massstorage system readable by the computer 12. The computer readable mediumincludes cooperating or interconnected computer readable media, whichexist exclusively on computer system 10 or are distributed amongmultiple interconnected computer systems 10 that may be local or remote.

In an illustrative embodiment of the present invention, the computersystem 10 preferably uses the Windows® 95 client/server operatingsystem. However, other client/server operating systems (e.g. WindowsNT™, OS/2®, by IBM, Mac OS, UNIX, Windows CE, etc.) could also be used.A client/server operating system is an operating system which is dividedinto multiple processes of two different types: server processes, eachof which typically implements a single set of services, and clientprocesses, which request a variety of services from the serverprocesses. Object oriented programming is used to design theclient/server operating system, and applications which run under theclient/operation system, where objects represent system resources.

For example, the Windows® 95 client/server operating system providesshareable resources, such as files, memory, processes and threads, whichare implemented as “objects” and are accessed by using “objectservices.” As is well known in the art, an “object” is a data structurewhose physical format is hidden behind a type definition. Datastructures, also referred to as records or formats, are organizationschemes applied to data so that it can be interpreted, and so thatspecific operations can be performed on that data. Such data structuresimpose a physical organization on the collection of data stored withincomputer memory 16 and represent specific electrical, magnetic ororganic elements.

An “object type,” also called an “object class,” comprises a data-type,services that operate on instances of the data type, and a set of objectattributes. An “object attribute” is a field of data in an object thatpartially defines that object's state. An “object service” implementsand manipulates objects, usually by reading or changing the objectattributes. “Object oriented design” is a software development techniquein which a system or component is expressed using objects.

An object typically has two components: a function table, containing apointer to each object member function (i.e., sometimes known as anobject method) defined in the object's class, and a data block,containing the current values for each object variable (i.e., datamembers, sometimes known as an object property). An application has somereference to an object through an object pointer. An application obtainsthis object reference by using some type of function call (direct orimplied) in which that function allocates an object block in computermemory, initializes the function table, and returns the reference to thecomputer memory to an application. The computer memory may be local ordistributed on a remote computer.

The Windows® 95 operating system allows users to execute more than oneprogram at a time by organizing the many tasks that it must perform into“processes.” The operating system allocates a portion of the computer'sresources to each process and ensures that each process's program isdispatched for execution at the appropriate time and in the appropriateorder.

In an illustrative embodiment of the present invention, processes areimplemented as objects. A process object comprises the followingelements: an executable program; a private address space; systemresources (e.g., communication ports and files) that the operatingsystem allocates to the process as the program executes; and at leastone “thread of execution.” A “thread” is the entity within a processthat the operating system kernel schedules for execution. As is wellknown in the art, each thread has an associated “context” which is thevolatile data associated with the execution of the thread. A thread'scontext includes the contents of system registers and the virtualaddress belonging to the thread's process. Thus, the actual datacomprising a thread's context varies as it executes.

The Component Object Model (COM) and Distributed Component Object Model(DCOM) are models used for object oriented programming. The COM and DCOMspecifies how objects within a single application or betweenapplications (e.g. client/server applications) interact and communicateby defining a set of standard interfaces. Interfaces are groupings ofsemantically related functions through which a client applicationaccesses the services of a server application.

Object Linking and Embedding (OLE), such as OLE Version 2 by theMicrosoft Corporation of Redmond, Wash., and ActiveX™ (networkactivation controls) are based in part on the Component Object Model andallows the creation of objects of different formats which operate ondata through defined interfaces, rather than operating on theapplications responsible for the data. ActiveX™ is based in part on OLEtechnologies. The object data can be embedded within an object, orlinked to it, so that only a link reference to the data is stored in theobject.

In a browsing environment 34 of an illustrative embodiment of thepresent invention shown in FIG. 2, a local computer 36 (e.g., computersystem 10 shown in FIG. 1) runs software, referred to herein as a“browser,” for unified browsing of electronic documents and other datafrom local sources (e.g., the memory system 16 of FIG. 1) and from acomputer network 38 (e.g., the Internet, an intranet). The browser canbe integrated with the operating system software, or can be a separateapplication software. The browser is typically an object orientedapplication. The illustrated remote computer network 38 is the Internet,which is described in the Background and Summary of the Invention above.In the illustrated browsing environment 34, the local computer 36connects to the computer network 38 over a telephone line 40 with amodem 42. Other physical connections to the computer networkalternatively can be used, such as an ISDN, T1, DS1 or other high speedtelecommunications connections and appropriate connection device, atelevision cable and modem, a satellite link, an optical fiber link, anEthernet or other local area network technology wire and adapter card,radio or optical transmission devices, etc. The invention canalternatively be embodied in a browsing environment for other public orprivate computer networks, such as a computer network of a commercialon-line service or an internal corporate local area network (LAN), anintranet, or like computer network.

Documents for browsing with the illustrated browser can reside as filesof a file system stored in the computer's secondary storage 32 (FIG. 1),or reside as resources at a remote computer 44 (also referred to as a“site” or “store”) connected to the computer network 38, such as a WorldWide Web site on the Internet. The illustrated document 46 residing atthe site or store 44 conforms with HTML standards, and may includeextensions and enhancements of HTML standards. However, the illustratedbrowser also can browse documents having other data formats (e.g.,Virtual Reality Modeling Language (VMRL), Microsoft® Word documents,etc.) from the local computer 36 or remote computer 44. In conformancewith HTML, the illustrated document 46 can incorporate other additionalinformation content 48, such as images, audio, video, executableprograms, etc. which also reside at the remote computer 44 or otherremote computers. The document 46 and information 48 preferably arestored as files in a file system of the remote computer 44. The document46 incorporates the information 48 using HTML tags and Uniform ResourceLocators (URLs) that specify the location of files or other Internetresources containing the images on the computer network 38. However,other locating formats can also be used.

When used for browsing documents, the illustrated browser displays thedocument in a window 50 or area of the local computer's 36 display 20allocated to the browser by the operating system. The illustrated window50 comprises a document display area 52 and user interface controls 54.The browser displays the document within the document display area 52 ofthe window 50. However, other display types could also be used. Thecomputers 36, 44 can also be network computers (NCs) which include onlyselected components of computer system 10.

The browser and other client applications within the local computer 34preferably work with documents (which have data formats other than thosenative to the browser or client application) by encapsulating thedocument's data into an associated object, and integrating with theobject using pre-defined interfaces as described more fully below. Thisallows full use of all the features described below.

Alternatively, the browser or other client application can work with adocument by launching an application program associated with thedocument and causing the associated application program to load thedocument and perform a specified operation on the document. In theMicrosoft Windows® 95 operating system, this is done by looking up theapplication program associated with the document's file name extensionin the system registry, (e.g., “.doc” for Microsoft® Word documents,“.vsd” for Shapeware's VISIO drawings, etc.) and a text string commandfor directing the program to perform a desired operation. Theapplication program associated with a document also may be identified inthe Microsoft Windows® operating system by matching a bit pattern atspecific offset into the file as also specified in the system registry.The browser or other client application patches the document's file nameinto the text string command and invokes the operating system's shellexecute service to execute the command. Shell execute is a well knownWindows® operating system service which issues a text string as acommand to the operating system's command interpreter (i.e., the“command.com” program in the Windows® operating system).

The text string generally is in the form of an MS-DOS command, whichspecifies a path and file name of the associated application program'sexecutable file, a flag for specifing the desired operation, and thedocument's path and file name. The command interpreter responds byparsing the text string, loading the application program specified inthe text string, and passing the flag and the document's path and filename as command line arguments into the application program. Theapplication program then “opens” (i.e., loads) the document and performsthe operation specified by the flag.

As was described above, it is desirable to add interactive or dynamicbehavior to a document 46 written in HTML and other formats by obtainingsoftware components from one or more remote computers. As is shown inFIG. 3, an illustrative embodiment of the present invention includes anautomatic software download system 56 with a software component downloadmodule 58, a data download module 60, a code verification module 62, anda code installation module 64.

When a request is made to download a desired software component storedon a remote computer 44, the software component download module 58determines if the desired software component is already installed on thelocal computer 36. If the desired software component is alreadyinstalled on the local computer 36, then the desired software componenton the local computer 34 is checked to see if a more recent version isavailable. If a more recent version of the desired software component isavailable, or if the desired computer software component is notavailable on the local computer 34, then it is downloaded in anasynchronous manner by the data download module 60. The softwarecomponent download module 58 uses a Uniform Resource Locator (URL) or anetwork search path to locate a desired software component. The URL andnetwork search path will be explained below.

Any software components downloaded to the local computer 36 are verifiedwith the code verification module 62. The code verification module 62checks a digital signature in a digital certificate included in thedownloaded software component to ensure the downloaded softwarecomponent is safe (e.g., computer virus and corruption free) on thelocal computer 34. The digital certificate is used to inform a user whocreated the software component and signed it with the digital signature.After it is verified by the code verification module 62, the downloadedcomputer software component is installed on the local computer 34 by thecode installation module 64.

In an illustrative embodiment of the present invention, system 56includes a software interface CoGetClassObjectFromUrl for the softwarecomponent download module 58, a software interface URL Moniker for thedata download module 60, a software interface WinVerifyTrust for thecode verification module 62, and a software interface ICodeInstall forthe code installation module 64.

In an illustrative embodiment of the present invention, the softwareinterfaces and corresponding software subroutines just described areavailable in the Internet Component Download Application ProgramInterface (API) for the Windows® 95 Operation System by MicrosoftCorporation of Redmond, Wash. The details of each of these interfaceswill be explained below. However, the modules of system 56 may also beimplemented as hardware modules, or a combination of software andhardware modules. In addition, other software subroutines, interfaces,and operating systems could also be used for system 56.

The system 56 is used with method 66 as is shown in FIG. 4 forautomatically locating 68, downloading 70, verifying 72, installing 74,registering 76, and returning 78 computer software components obtainedfrom a computer network 36 like the Internet. However, method 66 andsystem 56 are not limited to downloading software components for HTMLdocuments. Almost any type of computer software components can beobtained from a local or remote computer using system 56 and method 66for many types of files or documents.

In an illustrative embodiment of the present invention, computersoftware components (e.g., a control file) are automatically located 68using one of two designators: a URL or a network search path. The URL ornetwork search path are used to first locate 68 a control file on aremote computer. The control file can be a single portable executablefile or a file (e.g., a cabinet or initialization file) which containsone or more remote executable files, library files (e.g., Dynamic LinkLibrary (.DLL) files), or references to one or more remote executablefiles or library files. The control file is used to determine thelocation of the software components on one or more remote computers 44to download to the local computer 36.

In an illustrative embodiment of the present invention, the control fileis used to locate object oriented software components including: ObjectLinking and Embedding (OLE) components, ActiveX™ (network activation)components, Visual Basic components, Netscape™ ONE Plug-ins, Javacomponents or others to provide dynamic or interactive multimedia to auser. Moreover, software components can be downloaded to providefunctionality other than dynamic or interactive multimedia and thecomponents need not be in the form of object-oriented softwarecomponents.

Downloaded software components are automatically verified 72 by checkinga digital signature and a digital certificate contained within thesoftware components (e.g., with WinVerifyTrust). However, securitymeasures other than digital signatures and digital certificates couldalso be used to verify a software component. In another embodiment ofthe present invention, the software verification step 72 is optional.For example, on a corporate intranet, where all software componentsbehind a corporate firewall are automatically trusted and need noverification. The verified software components are then automaticallyinstalled 74 (e.g., with ICodeInstall) in various directories of a filesystem on the local computer 34. After installation the softwarecomponents are registered 76 (e.g., with DllRegisterServer orModuleUsage) in a registry database on the local computer 34. Theregistry database is used to keep track of which software components areinstalled on the local computer 34. In another embodiment of the presentinvention, the registration step 76 is optional. After registration,selected software components are returned 78 to a requestingapplication. Further details of method 66 will be explained below.

In an illustrative embodiment of the present invention, a networkbrowser such as the Microsoft Internet Explorer® version 3.0, usessystem 56 and method 66 to download and install object oriented softwarecomponents used for dynamic or interactive multimedia in HTML documents46. However, other applications can use system 56 and method 66 todownload and install executable software components from one or moreremote computers.

To use dynamic or interactive multimedia in HTML documents, HTML<OBJECT> tags are used. One or more HTML <OBJECT> tags are embedded intoa document written in HTML or some other programing or scriptinglanguage which permits HTML references. The <OBJECT> tags typicallypoint to object-oriented computer software components or some other fileformat that is executable or references an executable file.

The HTML <OBJECT> tag has multiple attributes including: DATA, CODEBASE,CLASSID, TYPE, ID, and CLASS attributes. The DATA attribute specifies aUniform Resource Locator (URL) referencing an object's data. TheCODEBASE attribute is an optional attribute used when the objectreferences a desired software component program. Besides the actuallocation of the desired software component, the “CODEBASE” URL in the<OBJECT> tag may also include an optional version number using thefollowing syntax:

“CODEBASE=http://www.foo.com/bar.ocx#Version=a,b,c,d”.

Where “a,b” in “#Version=a,b,c,d” represent the desired version of asoftware component on a remote server, and “c,d” represent the desiredversion of a local software component. The method 66 will download 70and process (72-78) the software component pointed to by the CODEBASEattribute only if the specified version number of the remote softwarecomponent is more recent than any existing version of the same softwarecomponent currently installed on the local computer 34. If a versionnumber is not specified for a software component, it is assumed that anyversion installed on the local computer 34 is proper to use. TheCODEBASE attribute can also be a URL fragment with the syntax

“CODEBASE=#Version=−1,−1,−1,−1”.

Specifying only “#Version=−1,−1,−1,−1” for the CODEBASE attribute causesa network search path to be used to find the latest version of a desiredsoftware component. The network search path will be explained below.

The CLASSID attribute is used to specify an object identifier. On eachcomputer (36,44) connected to the computer network 38, for example, theoperating system registry (also called the registration database) isused to store relevant information about object oriented componentsaccording to their CLaSs IDentifier (CLSID). An object registers itsCLSID in the operating system registry database to enable clientapplications (e.g., a network browser) to locate and load the executablecode associated with the objects. The HTML <OBJECT> CLASSID isequivalent to the object-oriented CLSID.

The CLSIDs are also given the alias “GUID,” which stands for GloballyUnique IDentifiers. Each object class is represented by a CLSID, a128-bit (16-byte) number that is assumed to be unique on computernetwork across space and time. A CLSID is a 16-byte value with aspecific structural definition that has an ASCII representation shownbelow as a group of hexadecimal digits within braces such as“{42754850-16b7-11ce-90eb-00aa003d7352}” (The groupings of the hexdigits and the hyphens are part of the ASCII representation as well).Application programs such as the network browser manipulate thestructural definition (e.g., the C/C++ structural definition) of theCLSID. The CLSID is used as the HTML <OBJECT> CLASSID.

The TYPE attribute specifies the Internet media type for the OBJECTdata. The ID attribute is used to define a document-wide identifier. TheCLASS attribute is used for applying a pre-determined style to an OBJECTelement. Remaining <OBJECT> tag attributes, like “ID, STYLE, DIR, ALIGN,WIDTH, HEIGHT, BORDER, HSPACE and USPACE” are known attributes in HTMLand, although previously used in a manner different from the presentinvention, are generally described in HTML 3: Electronic Publishing onthe World Wide Web by Dave Ragget, Jenny Lam, and Ian Alexander,Addison-Wesley, 1996.

An example <OBJECT> tag in a HTML document for an ActiveX™ Control isshown below.

<OBJECT

CLASSID=“classid:663CFEE:1A9B-22DC-AB3C-080036F12502”

CODEBASE=“http://www.microsoft.com/test.ocx#FileVersion=0,0,4,2”

>

</OBJECT>

where the CLASSID “663CFEE:1A9B-22DC-AB3C-080036F12502” shows an objectidentifier (i.e., CLSID) for the ActiveX™ Control “test.ocx”, theCODEBASE attribute gives the URL “http://www.msn.com/test.ocx” whichspecifies where to find the ActiveX™ Control file. </OBJECT> signifiesthe end of the <OBJECT> tag. If the ActiveX™ Control is not present onthe local computer, or if the ActiveX™ Control is already stored on thelocal computer and has a version earlier than 4.2, then it will bedownloaded to the local computer which will replace the current versionon the local computer.

After embedding one or more HTML <OBJECT> tags in a document written inHTML and storing the document on a remote computer 44 connected to acomputer network 38 (e.g., the Internet, an intranet) the document 46 isbrowsed with a network browser from the local computer 34.

When an HTML <OBJECT> tag is encountered in the document by the networkbrowser, the <OBJECT> tag is parsed to pull out <OBJECT> tag attributes(e.g., the CLASSID, CODEBASE, etc.). The network browser passes the<OBJECT> tag attributes to the software component download module 58 viathe CoGetClassObjectFromURL interface. If a network browser is not used,other applications could use method 66 and system 56 by sending theproper parameters to the CoGetClassObjectFromURL interface.

In an illustrative embodiment of the present invention, the singleinterface CoGetClassObjectFromURL manages method 66 and system 56.However, multiple interfaces could also be used. Any application thatwishes to download almost any software component from a remote computer44 connected to a computer network 38 like the Internet can do so bypassing the appropriate parameters to the CoGetClassObjectFromURLinterface.

The interface to the CoGetClassObjectFromURL interface is shown below.

STDAPI CoGetClassObjectFromURL (

[in] REFCLSID rclsid,

[in] LPCWSTR szCodeURL,

[in] DWORD dwFileVersionMS,

[in] DWORD dwFileVersionLS,

[in] LPCWSTR szContentTYPE,

[in] LPBINDCIX pBindCtx,

[in] DWORD dwClsContext,

[in] LPVOID pvReserved,

[in] REFIID riid,

[out] VOID **ppv);

Where [in] are input parameters and [out] are output parameters.

CoGetClassObjectFromURL accepts the following arguments:

Argument Type Description rclsid REFCLSID CLSID of the object that needsto be installed. If value is CLSID_NULL then szContentType is used todetermine the CLSID. szCodeURL LPCWSTR URL pointing to the code for theobject. This may point to an executable, to an .INF file, or to a .CABfile. If this value is NULL, then Internet Component Download will stillattempt to download the desired code from an object store server on anInternet Search Path dwFileVersionMS DWORD Major version number for theobject that needs to be installed. If this value and the next are both0xFFFFFFFF, then it is assumed that the latest version of the code isalways desired, an attempt to download new code will be made.dwFileVersionLS DWORD Minor version number for the object that needs tobe installed. If this value and the previous one are both 0xFFFFFFFF,then it is assumed that the latest version of the code is alwaysdesired, an attempt to download new code will be made. szContentTypeLPCWSTR MIME type that needs to be understood by the installed object.If rclsid is CLSID_NULL, this string is used to determine the CLSID ofthe object that must be installed. Note: this parameter is only usefulwhen trying to download a viewer for a particular media type, if theMIME type of the media is known but the CLSID is not. pBindCtx LPBINDCTXA bind context to use for downloading/installing component code. Theclient should register its IBindStatusCallback in this bind context toreceive callbacks during the download and installation process.dwClsContext DWORD Values taken from the CLSCTX enumeration specifyingthe execution context for the class object. pvReserved LPVOID Reservedvalue, must be set to NULL. riid REFIID The interface to obtain on thefactory object (typically IClassFactory). ppv VOID** Pointer in which tostore the interface pointer upon return if the call is synchronous.Returns S_OK Success. ppv contains the requested interface pointer.MK_S_ASYNCHRONOUS Component code will be downloaded and installedasynchronously. The client will receive notifications through theIBIndStatusCallback interface it has registered on pBindCtx.E_NOINTERFACE The desired interface pointer is not available. OtherCoGetClassObject error return values are also possible here.

In an illustrative embodiment of the present invention, the values forparameters passed to the CoGetClassObjectFromURL interface are readdirectly from an HTML <OBJECT> tag. For example, the szCodeURL,dwFileVersionMS, and dwFileVersionLS are specified inside an <OBJECT>tag with “CODEBASE=http://www.foo.com/bar.ocx#Version=a,b,c,d” whereszCodeURL is “http://www.foo.com/bar.ocx”, dwFileVersionMS is “a,b”, themajor version of a file on remote server (e.g., a software provider suchas Microsoft), and dwFileVersionLS is “c,d”, the version of a file onthe local computer. The CoGetClassObjectFromURL interface is responsiblefor managing method 66 and system 56. A software component requestedwith method 66 is typically a factory class object. A class factorygenerates actual object class instances of an object and is known tothose skilled in the art.

As is shown in FIG. 5, the CoGetClassObjectFromURL interface uses method80 to locate a control file on a remote computer 44. If it specifies 82a CLSID, CoGetClassObjectFromURL checks to see if the desired softwarecomponent (i.e., the control file) is registered and installed 84 on thelocal computer 36 with the right version number 86. If it does notspecify a CLSID (i.e., has a value of CLSID_NULL),CoGetClassObjectFromURL will choose the appropriate CLSID byinterpreting the Multipurpose Internet Mail Extension (MIME) 88 typespecified in the szContentType parameter. MIME provides a standardmechanism for messages to be exchanged over computers connected to theInternet. See Internet Standard Document: RFC 1521 for specific detailson MIME.

If the desired software component is registered and installed on thelocal computer, and if the version number is correct, then the desiredsoftware component is obtained from the local computer 36. If thedesired software component is not registered and installed on the localcomputer, or if the version number is incorrect, then the desiredsoftware component is obtained from the remote computer 44.

To obtain the desired software component from the remote computer 44,the szCodeURL parameter is checked 90. If the szCodeURL parameter is notNULL, then an attempt is made to locate the desired software componentwith the URL stored in szCodeURL. If the URL is valid 92, the desiredsoftware component will be downloaded 70 (FIG. 4) to the local computer36. If the szCodeURL is NULL, or the specified URL is invalid, a then anetwork search path is used to locate the software component 94. Thenetwork search path is specified as shown below.

CodeBaseSearchPath=<URL₁>; <URL₂>; . . . <URL_(m)>; CODEBASE URL;

<URL_(m+1)>; . . . <URL_(n−1)>; <URL_(n)>

This search path is made accessible to the CoGetClassObjectFromURLinterface. For example, using Microsoft's Internet Explorer® 3.0 runningon Windows® 95, the search path is stored in the system registry. Onother operating systems or with other software applications, this searchpath may be stored elsewhere as long as it is accessible to theCoGetClassObjectFromURL interface. On Windows operating systems, thenetwork search path is specified in a string in the registry databaseunder the key:

KEY LOCAL MACHINE\Software\Microsoft\Windows\

CurrentVersion\Internet Settings\CodeBaseSearchPath

However, other registry database keys could also be used. The value forthis key is a string of szCodeURL parameters.

Each of URLs URL₁ through URL_(N) in the network search path areabsolute URLs pointing to HTTP servers acting as “Object Stores” 44.However, other formats could also be used for the network search string.

As is shown in FIG. 6, the CoGetClassObjectFromURL interface usingmethod 96 will first try locating 68 (FIG. 4) the desired control fileusing URL₁ through URL_(m) (98-102). If the desired control file cannotbe located using URL₁ through URL_(m), CoGetClassObjectFromURL will trythe location specified in the szCodeURL parameter (e.g., correspondingto the CODEBASE attribute in the <OBJECT> tag) 104. If the desiredcontrol file cannot be located using the szCodeURL search path,CoGetClassObjectFromURL will try the locations specified in locationsURL_(m+1) through URL_(N) (106-110). If this search fails, then thedesired control file cannot be located. The network search using anetwork search path will use the first successful response from a serverand will not subsequently continue searching for newer versions ofcomponents. However, newer versions of software components can also besearched for.

If the CODEBASE keyword is not included in the CodeBaseSearchPath key,then calls to CoGetClassObjectFromURL will not check the szCodeURLlocation for downloading code. By removing the CODEBASE keyword from theCodeBaseSearchPath, corporate intranet administrators can effectivelydisable corporate users from accessing any remote computer to obtain acomputer software component specified by a HTML <OBJECT> tag. This alsoallows registration of default Object Store locations 44 on the WorldWide Web, where browsers can find code when no CODEBASE location isexplicitly specified. In addition, by removing the CODEBASE keyword fromthe CodeBaseSearchPath and pointing URL₁ through URL_(N) to intranetsites, corporate intranet administrators can effectively disablecorporate users from accessing software components from any computersoutside a local intranet.

In an alternative embodiment of the present invention, the networksearch path can be used in an alternative way: the URLs in the networksearch path (98-102, 106-110) will be searched for a control file aftertrying the location specified in the szCodeURL parameter forCoGetClassObjectFromURL, (e.g., after trying the location specified inthe CODEBASE attribute 104 from a HTML <OBJECT> TAG).

In an illustrative embodiment of the present invention, an Object Storeon the network search path is an HTTP server that services requests fora desired control file. CoGetClassObjectFromURL will try to locate thecontrol file from the various Object Stores in the search path.Specifically, an Object Store will receive an HTTP POST request withdata in the format below:

CLSID={class id}

Version=a,b,c,d

MIMETYPE=mimetype

All the values above are optional, although at least one of CLSID orMIMETYPE parameters must be present. The Object Store parses thisinformation, checks an internal database, and either fails, or redirectsthe HTTP request to the control file on the next remote computer in thenetwork search path.

The HTTP POST parameters are processed by the Object Store as follows:If CLSID is provided with no version number, then the most recent objectmatching the CLSID will be returned. If the CLSID is provided withVersion, then the object matching the CLSID and with the highest versionnumber greater than or equal to Version will be provided. If no objectis available that matches the CLSID with a large enough version number,then the HTTP error (e.g., the 404 error) will be returned. MIMETYPEwill be ignored when CLSID is provided.

If no CLSID is provided, but MIMETYPE is provided, then the first objectfound in the database that matches the MIMETYPE will be returned.Version, if provided, is treated as described above. If neither CLSID orMIMETYPE is provided then the HTTP error return code “400 Bad Request”will be returned.

In addition to the HTTP POST data described above, queries to ObjectStores may also include HTTP headers for ACCEPT (MIME type) andACCEPT-LANGUAGE, thus specifying the desired platforms andlanguage-localized implementation for a component. HTTP headers aretypically added to all HTTP requests made by method 66 and system 56.This allows Object Stores to serve different code implementations fordiffering platforms or even different languages.

The illustrated and alternative embodiments of the present inventiondescribed above assume that all computer software storage serverssearched with the network search path are active HTTP servers capable ofhandling HTTP POST requests and querying an object database to find thedesired software components. In another alternative embodiment of thepresent invention, non-HTTP servers can also be used in the networksearch path (e.g., FTP servers and standard file servers).

The control file located 68 on a remote computer can be, for example, aportable executable file, a cabinet file, or an initialization file. Aportable executable (PE) is a single executable file that is downloaded,verified, registered and installed on the user computer according tomethod 66. The portable executable is typically an OLE control orActiveX™ (network activation) control file (e.g., .OCX), a Dynamic LinkLibrary file (e.g., .DLL), or a executable file (.EXE). OLE control,ActiveX™, Dynamic Link Library, and executable files are known to thoseskilled in art.

A single portable executable file is the simplest way to package asoftware component to provide dynamic or interactive multimedia.However, when a single portable executable is used, the file istypically not compressed, and the software component will not beplatform independent unless a HTTP server negotiates a platformindependent format. The HTTP server negotiation will be explained indetail below.

A cabinet file (e.g., CAB) can be used for the control file. The cabinetfile contains one or more files, all of which are downloaded together ina compressed “cabinet.” One file in the cabinet is an initializationfile (e.g., .INF) providing further installation information. This .INFfile may refer to files in the cabinet as well as to files at otherURLs. Using a cabinet file requires authoring of a .INF and packaging ofa CAB file, but in return it provides file compression. File compressionis completed with Lempel-Ziv compression, which is known in the art.However, other compression formats could also be used.

Cabinet files can be created with the DIANTZ.EXE tool by MicrosoftCorporation. However, other cabinet file creation tools can also beused. The DIANTZ.EXE tool takes a directive file (e.g., .DDF), whichspecifies how to create a cabinet file, and creates a cabinet file. TheDIANTZ.EXE is used with the following command line:

DIANTZ.EXE/f directive_file.ddf

where the “If” attribute tells the DIANTZ.EXE tool to use the file“directive_file.ddf” to create the cabinet file. An example directivefile, CIRC3.DDF is shown below.

; DIAMOND directive file for CIRC3.OCX+CIRC3.INF .OPTION EXPLICIT ;Generate errors on variable typos .Set CabinetNameTemplate=CIRC3Z.CAB;** The files specified below are stored, compressed, in cabinet files.Set Cabinet=on .Set Compress=on circ3.INF circ3.OCX

The example directive file shown above would be used to create a cabinetfile (e.g., “.Set Cabinet=on”) containing two compressed (e.g., “.SetCompress=on”) files: circ3.INF and circ3.OCX where “circ3.INF” is thesingle initialization file and “circ3.OCX” is the desired softwarecomponent for dynamic or interactive multimedia. The .OCX file extensionsignifies an OLE control or ActiveX™ (network activation control) file.Comments are designated with a semi-colon “;”. As was discussed abovefor the portable executable, the cabinet file will also not be platformindependent, except with HTTP server negotiation which will be explainedbelow.

A stand-alone initialization file (.INF) can also be used for thecontrol file. This file specifies various files that need to bedownloaded and setup. The syntax of the .INF file allows URLs pointingto files to download, and provides platform independence by enumeratingchoices for various platforms. An example initialization file is shownbelow.

;Sample INF file for CIRC3.OCX [Add.Code] circ3.ocx=circ3.ocxrandom.dll=random.dll mfc40.d11=mfc40.dll foo.ocx=foo.ocx [circ3.ocx];lines below specify that the specified circ3.ocx (clsid, version) needsto be installed on ;the system. If doesn't exist already, can bedownloaded from the given location (a .CAB) ;note: if “thiscab” isspecifled instead of the file location, it is assumed that the ;desiredfile is present in the same .CAB cabinet that the INF originated from;otherwise, if the location pointed to is a different .CAB, the newcabinet is also downloaded and ;unpacked in order to extract the desiredfile file=http://www.code.com/circ3/circ3.cabclsid={9DBAFCCF-592F-101B-85CE-00608CEC297B} FileVersion=0,0,1,2[random.dll] ;lines below specify that the random.dll needs to beinstalled in the system ;if this doesn't exist already, it can bedownloaded from the given location.file=http://www.code.com/circ3/random.dll ;Note that the FileVersion isoption, and it may also be left empty, meaning that any version is ok.FileVersion= DestDir=10 ;DestDir can be set to 10 or 11 (LDID_WIN orLDID_SYS by INF convention) ;this places files in \windowsor\windows\system, respectively ;if no dest dir specified (typicalcase), code is installed in the fixed occache directory. [mfc40.dll];leaving the file location empty specifies that the installation ;needsmfc40 (version 4,0,0,5), but it should not be downloaded. ;if this fileis not already present on the client machine, component download failsfile= FileVersion=4,0,0,5 [foo.ocx] ;leaving the file location emptyspecifies that the installation ;needs the specified foo.ocx (clsid,version), but it should not be downloaded. ;if this file is not alreadypresent on the client machine, component download fails file=clsid={DEADBEEF-592F-101B-85CE-00608CEC297B} FileVersion=1,0,0,143

The sample .INF file shown above can be used to install the files“circ3.ocx, random.dll, mfc40.dll, and foo.ocx” where the .OCX fileextension signifies an OLE control or ActiveX™ control (networkactivation) file and the .DLL file extension signifies a Dynamic LinkLibrary file. OLE controls, ActiveXTm controls and Dynamic Link Libraryfiles are known to those skilled in the art.

The .INF file has instructions to install each of the necessary files,and comments are again designated with a semi-colon “;”. For example,the .INF file specifies that the “circ3.ocx” file needs to be installedon the local computer with a“clsid={9DBAFCCF-592F-101B-85CE-00608CEC297B}.” “FileVersion=0,0,1,2” isused to check a local version of a file to see if it is earlier thanVersion 1.2. If it is, it will be downloaded to the local computer. The“circ3.ocx” can be downloaded from a remote computer in a cabinet fileusing the URL “file=http://www.code.com/circ3/circ3.cab.” The“FileVersion=” attribute for the “random.dll” file is empty, so that anyversion of this file is ok. The “file=” attribute is empty for“mfc40.dll” and “foo.ocx” which signifies that these files should not bedownloaded to the local computer. If these files don't exist on thelocal computer, then the downloading fails.

The initialization file also provides platform independence for HTTP andnon-HTTP servers which store the desired software components. It ispossible to create platform-independent setup scripts that pull desiredsoftware components from different locations depending on the desiredplatform. A sample platform-independent .INF file would include a textsuch as the following:

[circ3.ocx] ; lines below specify that the specified circ3.ocx (clsid,version) needs to be installed on ; the system. If doesn't existalready, can be downloaded from the given location (a .CAB)file-win32-x86=file://products/release/circ3/x86/circ3.cabfile-win32-mips=file://products/release/circ3/mips/circ3.cabfile-mac-ppc=ignore ; the ‘ignore’ keyword means that this file is notneeded for this platform clsid={9DBAFCCF-592F-101B-85CE-00608CEC297B}FileVersion=1,2,0,0

The “file-x-y” syntax used in the .INF file is expanded to“file-%opersys%-%cpu%”, (e.g., “file-win32-mips” where %opersys%=“win32”and %cpu%=“mips”) allowing the .INF file to specify multiple locationswhere various platform-dependent modules can be found and downloaded.Valid values for %opersys% and %cpu% attributes are explained below.

The following MIME types will be used to describe PEs (portableexecutables - .EXE, .DLL, .OCX), cabinet files (.CAB), and setup scripts(.INF):

File description MIME Type PE (portable executable) -application/x-pe-%opersys%-%cpu% .EXE, .DLL, .OCX Cabinet files - .CABapplication/x-cabinet-%opersys%-%cpu% Setup scripts - .INF (platformapplication/x-setupscript independent)

The %opersys% and %cpu% attribute values shown below will specify theoperating system and CPU for the desired platform desired softwarecomponents will be executed on. For example, the MIME type for a Win32cabinet file running on an Intel® x86-architecture processor (whethermanufactured by Intel Corporation or another company) would beapplication/x-cabinet-win32-x86. The following are valid values for%opersys% and %cpu%:

Valid values for %opersys% Meaning win32 32-bit Windows ® operatingsystems (Windows95 or Windows NT) mac Macintosh ® operating system<other> will be defined as necessary Valid values for %cpu% Meaning x86Intel ® x86 family of processors ppc Motorola ® PowerPC architecturemips MIPS ® architecture processors alpha DEC ® Alpha architecture

However, more or fewer values could also be used.

When the desired software component is on a non-HTFP server (e.g., at anintranet or local LAN location), a .INF file can be used to achieveplatform independence by specifing different URLs for files to bedownloaded for different platforms.

Platform independence for HTTP servers which store the desired softwarecomponents is also provided without using an initialization file. AnHTTP ACCEPT header MIME request type is used to provide platformindependence. The MIME request type specifies which platform the code isto run on, thus allowing platform independence when the CODEBASEattribute or the network search path is used.

After locating 68 (FIG. 4) a desired information file, the necessarysoftware components are downloaded 70 (FIG. 4)with a data downloadmodule 60 (FIG. 3). The CoGetClassObjectFromURL interface uses the URLmoniker interface to download 70 the necessary software componentsasynchronously from one or more remote computers 44. However, otherinterfaces could also be used to download the necessary softwarecomponents. The URL moniker interface is described in greater detail inURLMON.DOC and ASYNCMON.DOC in the ActiveX™ Software Development Kit(SDK) by Microsoft.

The URL moniker interface uses the IBindStatusCallback interface, whichis implemented in an application program like the network browser, topass status information back to the application program. TheIBindStatusCallback interface enables the browser to tell the user whenthe download 70, verification 72, registration 74, and installation 76steps are complete.

The client of the CoGetClassObjectFromURL interface (e.g., the networkbrowser) will receive notification about the download/install processvia the provided IBindStatusCallback interface. During the downloadprocess , the following additional values (from the BINDSTATUSenumeration of Windows 95, for example) may be passed back as theulStatusCode parameter for IBindStatusCallback::OnProgress.

Value Description BINDSTATUS_BEGINDOWNLOADCOMPONENTS The downloadoperation has begun downloading code for software components that willbe installed before the object may be instantiated. The szStatusTextaccompanying IBindStatuscallback::OnProgress provides the display nameof the component being downloaded. BINDSTATUS_INSTALLINGCOMPONENTS Thedownload operation has downloaded code and is installing it. TheszStatusText accompanying IBindStatusCallback::OnProgress provides thedisplay name of the component being installed.BINDSTATUS_ENDDOWNLOADCOMPONENTS The download operation has finisheddownloading and installing all necessary code. The szStatusTextaccompanying IBindStatusCallbackOnProgress provides the display name ofthe newly installed component.

Since the downloading 70 of software components occurs asynchronously,the CoGetClassObjectFromURL interface will often return immediately witha return value of E_PENDING. At this point, the IBindStatusCallBackmechanism is used to communicate the status of the download operation tothe client (e.g., the network browser). To participate in thiscommunication, the client implements IBindStatusCallback and registersthis interface in pBindCtx passed into CoGetClassObjectFromURL usingRegisterBindStatusCallback. The client can expect to be called withcallback notifications for OnStartBinding (providing an IBinding forcontrolling the download), OnProgress (reporting progress),OnObjectAvailable (which returns the desired object interface pointer),and OnStopBinding (which returns error codes in case of an error). Forfurther negotiations, the client also implement ICodeInstall to installthe desired software component as is described below. However, otherdownloading and callback processes can also be used.

After downloading 70 the necessary software components to the localcomputer 36, the software components are verified 72 with a codeverification module 62. CoGetClassObjectFromURL uses the WinVerifyTrustinterface and the ICodeInstall interface to ensure the necessarysoftware components are safe and trusted, and to ensure that the userwants to install the software components. However, other interfacescould also be used to verify and install the necessary softwarecomponents. ICodelnstall is implemented by the downloading client (e.g.,the network browser), and is used whenever installation of softwarecomponents needs some service (e.g., verification) before the downloadcan be negotiated correctly.

A code install operation 74 requires additional services from the clientin order to complete the negotiation necessary for a download operation70. Such services are requested usingIBindStatusCallback::QueryInterface. The specific interface requested inIBindStatusCallback:: QueryInterface is ICodeInstall. This interface isimplemented by a client application (e.g., a network browser). TheICodeInstall interface has two member functions: NeedVerificationUI andOnCodeInstallProblem. The ICodeInstall interface and functions are shownbelow.

interface ICodeInstall : IUnknown {  HRESULT NeedVerificationUI(   [out]HWND* phwnd);  HRESULT OnCodeInstallProblem(   [in] ULONG ulStatusCode,  [in] LPCWSTR szDestination,   [in] LPCWSTR szSource,   [in] DWORDdwReserved);  }; ICodeInstall::NeedVerificationUI is called to displayUser Interface (UI) for verification of downloaded code. When a clientis called with this function, it has the opportunity to clear a messagequeue of its parent window before allowing UI to be displayed. If theclient does not wish to display UI, code verification may continue, butcomponents may fail to be installed. The parameters forICodeInstall::NeedVerificationUI are explained below.HRESULT NeedVerificationUI([out] HWND* phwnd);

Argument Type Description phwnd HWND* Client-provided HWND of the parentwindow for displaying code verification UI. If this parameter is NULL,the desktop window is used. If the value is INVALID_HANDLE_VALUE, or ifthe return value is S_FALSE, then no code verification UI will bedisplayed, and certain necessary components may not be installed.Returns S_OK Success. S_FALSE No window is available. E_INVALIDARG Theargument is invalid. ICodeInstall::OnCodeInstallProblem is called whenthere is a problem with code installation. This notification gives theclient a chance to resolve the problem, often by displaying UI, or byaborting the code installation process. The parameters forICodeInstall::OnCodeInstallProblem are explained below.HRESULT OnCodeInstallProblem(  [in] ULONG ulStatusCode,  [in] LPCWSTRszDestination,  [in] LPCWSTR szSource,  [in] DWORD dwReserved);

Argument Type Description ulStatusCode ULONG Status code describing whatproblem occurred. A member of CIP_STATUS. szDestination LPCWSTR The nameof the existing file that was causing a problem. This may be the name ofan existing file that needs to be overwritten, the name of a directorycausing access problems, or the name of a drive that is full. szSourceLPCWSTR Name of the new file to replace the existing file (ifapplicable). dwReserved DWORD Reserved for future use Returns S_OKContinue the installation process. If there was an “access denied” ordisk-full problem, retry the installation. If there was an existing file(newer or older version), overwrite it. S_FALSE Skip this particularfile, but continue with the rest of the code installation process. Note:this is the typical response for the CIP_NEWER_VERSION_EXISTS case.E_ABORT Abort the code installation process. E_INVALIDARG The givenarguments are invalid.

The ulStatusCode parameter above is one of the following values:

Value Description CIP_DRIVE_FULL The drive specified in szDestination isfull. CIP_ACCESS_DENIED Access to the file specified in szDestination isdenied. The client is required to take a sequence of steps to possiblycorrect the situation. The client could check its own state to see ifthe file in question or the component it belongs to is in use by theclient and close the file or release the component and call COM to freeunused libraries in the process. If it cannot locate the file orcomponent, it should display UI to the user suggesting that they closeother applications in the system to retry the operation. The operationcan be retried by returning S_OK. Returning S_FALSE will ignore thisfile and proceed with the rest of the installation. Any error returnswill cause the code download to abort. CIP_OLDER_VERSION_EXISTS Anexisting file (older version) specified in szDestination needs to beoverwritten by the file specified in szSource. CIP_NEWER_VERSION_EXISTSA file exists (specified in szDestination) that is a newer version of afile to be installed (specified in szSource) CIP_NAME_CONFLICT A fileexists (specified in szDestination) that has a naming conflict with afile to be installed (specified in szSource). The existing file isneither a newer nor an older version of the new file—they are mismatchedbut have the same file name. CIP_TRUST_VERIFICATION_COMPONENT_MISSINGThe code installation process cannot find the necessary component (e.g.,WinVerifyTrust) for verifying trust in downloaded code. szSourcespecifies the name of the file that cannot be certified. The clientshould display UI asking the user whether or not to install theuntrusted code, and should then return E_ABORT to abort the download,S_OK to continue anyway, or S_FALSE to skip this file but continue(usually dangerous). CIP_NEED_REBOOT The self-extracting EXE or ‘hook’(either Win32 INF section or a custom setup program hook run using therun=<cmd-line>) in the hook section updated components in use that canonly be used after a reboot. The client should display UI and Shutdownwindows if the user agrees to reboot the machine for the changes to takeeffect. The INF filename or command line of the EXE that caused thereboot is in szDestination. Returning E_ABORT will abort the download.CIP_EXE_SELF_REGISTRATION_TIMEOUT The EXE that was spawned toself-register (may also be a self-extracting EXE) is still pendingcompletion. This is usually called out when the client callsIBinding::Abort() while waiting for the self-extracting EXE to complete.The command line of the EXE is available in szDestination. The clientshould display UI to the user to warn that installation on the page isincomplete. The return value of S_OK from the callback will cause acontinued wait for the EXE to complete. S_FALSE will abandon the EXE andproceed with the rest of the installation. Any error returns will causeabortion of the code download. CIP_UNSAFE_TO_ABORT Code download is insetup phase and one or more components may have already been installedirreversibly rendering unknown the state of the setup of the componentin question. This notification is issued when the client callsIBinding::Abort() while in setup phase. The return value of S_OK willcause Abort() to return with S_FALSE and the code download willcontinue. Any other return will cause the code download to abort and thestate of the component is not guaranteed.

After the necessary software components are downloaded, theWinVerifyTrust interface checks to see if the downloaded componentspossess a digital signature. However, other verification interfacescould also be used. If the downloaded software components posses adigital signature, the WinVerifyTrust interface validates the digitalsignature and its corresponding digital certificate. The digitalcertificate describes who issued the software component and who createdthe digital signature. If the downloaded software components do notpossess a digital signature, or if the corresponding signature was notissued by a trusted authority, WinVerifyTrust gives the client-side(e.g., network browser) user the option of whether or not to trust thecode and install it on the local computer 36. Before asking forverification on its own, WinVerifyTrust usesICodeInstall::NeedVerificationUI to confirm that it is appropriate todisplay the appropriate UI for the user of the local computer 34.

After the code has been verified 72, the control file is installed 74 onthe local computer 34 with a code installation module 64. As is shown inFIGS. 7A-7B, method 112 installs 74 and registers 76 the control file.If the control file is a single portable executable file (e.g., .EXE,.OCX, DLL) 114, the single portable executable file is installed 116 onthe local computer 34 by CoGetClassObjectFromURL. If the control file isnot a single portable executable 118 (i.e., the file is a .INF or a CABfile), then each of the files referenced in the initialization orcabinet file are installed 120-124 on the local computer 34.

In an illustrative embodiment of the present invention, most of thedownloaded software components are installed in a permanent cache storein an operating system directory called “windows\occache.” However,other directories could also be used. Some components (e.g., helper DLLsthat need to be on the system PATH but currently are not) will also beinstalled in the “\windows” and “\windows\system” directories. However,other directories could also be used. If there are any problems duringinstallation (e.g., a full disk, access violations, existing older/newerversion of a file, etc.), the code install interface functionICodeInstall:OnCodeInstallProblem is called to make the user aware ofthe problem.

If the portable executable file is an .OCX or a .DLL file 126, it isregistered by calling the DllRegisterServer interface 128. TheDllRegisterServer interface is an interface which registers a softwarecomponent in the registry database of the operating system. However,other registering interfaces could also be used. If the portableexecutable file is a .EXE file 130 (FIG. 7B), the .EXE is registeredduring execution with the run-time parameter of “/RegServer” 132. Thisrun-time parameter registers the .EXE file in the registry database ofthe operating system.

In an illustrative embodiment of the present invention, self-registeringsoftware components are used because the .INF format does not providesyntax for changing registry information (for security reasons). For.OCXs, .DLLs, and .EXEs marked as “OleSelfRegister” in the Versionresource, self-registration will be attempted. For .DLLs and OCXs, thismeans loading the .DLL library and calling DllRegisterServer. For .EXEs,this means running the .EXE with the run-time parameter of “/RegServer”.This ensures that software components implemented as local servers (e.g.winword.exe) are registered correctly. If an object is not marked as“OleSelfRegister” but registration is necessary, or if it is desired toover-ride the “OleSelfRegister” flag, the following lines can be addedto an .INF file:

[foo.ocx] RegisterServer=no ; don't register even if markedOleSelfRegister  or RegisterServer=yes ; register this even if notmarked OleSelfRegister. This   is the typical workaround for getting old   ; controls to register

Software components that are a self-extracting .EXE may remainunregistered because the “OleSelfRegister” flag is ignored if the URLpoints directly at a .EXE file. In this case it is assumed that this isa self-registering .EXE, and this enables self-extracting .EXEs to workcorrectly as long as they ignore the “/RegServer” command-lineparameter. Supporting self-extracting .EXEs enables very complex setupmechanisms to be launched automatically. However, if a self-extracting.EXE is called via this mechanism, then any components that it installswill not be automatically tracked. Such components are permanentlyinstalled and may not be available for future cleanup. Every client(e.g., the network browser) of a software module (e.g., .OCX, .DLL,.EXE) is expected to increment and decrement the existing SharedDLLssection in the registry database when the components are registered toallow the operating system to keep track of how many clients are sharingthe software components.

Returning to FIG. 7B, if the file is a .INF or .CAB file, all downloadedsoftware components are registered using a new section in the registrydatabase called Module Usage 136 that keeps track of such components.The Module Usage section in the registry holds a list of “owners” and“clients” for each software module. Thus, the registry can keep track ofhow many clients a module has (i.e., the SharedDLL count), as well aswhat software applications executing on the local computer are using thesoftware module. The registry entries for ModuleUsage use the followingsyntax:

[ModuleUsage] [<Fully Qualified Path&File Name>] .FileVersion=a,b,c,d.Owner = Friendly Name/ID of Owner <Client ID > = <info peculiar to thisclient> <Client ID > = <info peculiar to this client> A ModuleUsagesection in a sample registry might be: Under MyComputer\HKEY_LOCAL_MACHINE\Software\Microsoft\Windows \CurrentVersion:[ModuleUsage] [c:\windows/system/mfc40.dll] .FileVersion=1,4,0,0.Owner={CLSID of main object rclsid passed to CoGetClassObjectFromURL}{CLSID of main object rclsid passed to CoGetClassObject FromURL}=<anyinfo, or default> AnotherAppID=<any info, or default>

The parameters of ModuleUsage are as follows:

Key name Description <Fully Qualified This is the full path of theshared module. This name has to use “/”s Path&File Name> instead of “\”sbecause the “\” is an invalid char in a key name. .Owner The applicationthat installs the shared module and creates the original ModuleUsagesection will put some identifier in the Owner key section. If the DLLalready existed on the system then and this Module Usage key did notexist then the .Owner key should be set to “Unknown” and the DLL shouldnot be removed on uninstall. The owner should always also enlist itselfas a client. .File Version The version number for the shared module.<Client ID> ID of a client who is using the shared module. The valuecorresponding to each client key contains client specific information.When the client is Internet Component Download, the <Client ID> is{CLSID of main object rclsid passed to CoGetClassObjectFromURL}, and theclient-specific information is a number which serves as a referencecount. For other clients, the client-specific information should be thefull path of the client, so that if the client is accidentally deletedit is possible to do garbage collection.

To permit code caching, the “SharedDLLs” section in the registrydatabase is not used exclusively since reference counts are oftenincorrectly inflated. For example, any application that is re-installedon the local computer increases the reference count in the SharedDLLssection of the registry database even though the software componentalready had been incremented previously. However, in an illustrativeembodiment of the present invention, every client (e.g., networkbrowser) of a software module is expected to increment and decrement theexisting SharedDLLs section in the registry database as well (a clientonly increments this value once when it adds itself as a client underModuleUsage). This is to allow a migration path for applicationscurrently implementing only SharedDLLs scheme.

The ModuleUsage registry information complements the reference counts inthe SharedDLLs section by remembering which clients are actually using ashared module. The SharedDLLs counting scheme is correct when used withModuleUsage registry information and allows caching of downloaded codein the permanent cache store. Furthermore, when downloading files, theModuleUsage registry information is used as an efficient shortcut forverifying whether a file needs to be overwritten because it is anout-of-date version. In another embodiment of the present invention, theregistering step 76 is optional.

Downloaded code installed in the permanent cache store can be removedmanually or automatically. In one embodiment of this invention, a useris allowed to clean up downloaded code, either through the UI of theapplication program (e.g., the network browser) or via UI exposed by theoperating system itself (e.g. the Windows® 95 “shell.” In anotheralternative embodiment of the present invention, ModuleUsage informationis used by the CoGetClassObjectFromURL interface to automatically detectold or unused downloaded code, and automatically delete such code fromthe permanent cache store.

In another embodiment of the present invention, software can be located68, downloaded 70 and installed 74, with the verifying 72 andregistering 76 steps optional. This allows a user to control more of theautomatic code downloading method with other software applicationschosen by the user.

For example, a “hook” mechanism is provided to override or customizesteps of method 66. In the illustrative embodiment of the presentinvention, there are two types of hooks: Unconditional (e.g., for asetup program) and Conditional (e.g., for a version of an existingsoftware component) hooks. Unconditional hooks are hooks that are alwaysexecuted. Conditional Hooks are executed only when a certain selectedcondition evaluates to TRUE. Hooks are added to the .INF file describedabove.

Unconditional hooks are used in [Setup Hooks] section of the .INF file.For Unconditional Hooks, the “CODEBASE=” attribute points to a cabinetfile “foo.cab” that contains a “foosetup.exe”, “foo.ocx” and “foo.inf.”file. The setup file “foosetup.exe” run with the “/q” parameter willinstall the “foo.ocx” file silently in the “windows\occache” directorydescribed above.

For Unconditional hooks, an example initialization file “foo.inf”includes the following:

[Add.Code]

[Setup Hooks]

hook1=hook1

[hook1]

run=%EXTRACT_DIR%\foosetup.exe/q

When the cabinet file foo.cab is opened, it is verified and then the.INF file is processed. Since the [Add.Code] section is empty, the[Setup Hooks] section is processed. The files in the cabinet file“foo.cab” are installed in a unique temporary directory and the commandline listed in the “run=” attribute is executed (i.e.,run=%EXTRACT_DIR%\foosetup.exe/q”). All the files left in the temporarydirectory after the completion of “foosetup.exe” including“foosetup.exe” are discarded. However, other commands could also be usedfor the Unconditional Hooks.

Conditional Hooks are run only when a certain condition is evaluated asTRUE. This is typically when the [Add.Code] section points at a certainsoftware component and that software component is not available on theclient computer. The above example for Unconditional Hooks could berewritten using Conditional Hooks.

For Conditional Hooks the “CODEBASE=” attribute also points to a cabinetfile “foo.cab” that contains a “foosetup.exe”, “foo.ocx” and “foo.inf”file. The file setup file “foosetup.exe” run with the “/q” parameteralso installs the file “foo.ocx” silently in the “windows\occache”directory as was described above.

For Conditional Hooks, an example initialization file “foo.inf” includesthe following:

[Add.Code]

foo.ocx=foo.ocx

[foo.ocx]

Clsid={. . . }

hook=hook1

[hook1]

run=%EXTRACT_DIR%\foosetup.exe/q

When the .INF is opened, it is processed using the [Add.Code] attribute.When the [foo.ocx] section is processed, the Clsid, (e.g. for “foo.ocx”)is used to determine if it is registered or available on the clientcomputer by checking the operating system registry. If “foo.ocx” is notregistered on the client computer, the hook mentioned in the [hook1]parameter is executed. The execution of [hook1] section is identical tothe description of the hook as an Unconditional Hook, but occurs onlyafter checking the Cisid of “foo.ocx.” However, other commands couldalso be used for the Conditional Hooks.

Conditional Hooks can be used to make the verifying 72 and registering76 steps of method 66 conditional (i.e., optional). This allows a userto use method 66 and system 56 to simply locate, download, and install adesired software component without verification or registration. Theverification and/or registration steps could be accomplished by methodsdifferent than those described in connection with method 66 and system56 giving the user greater flexibility over the use of the softwarecomponents downloaded and installed on the local computer.

In another embodiment of the present invention, the HTML tag <EMBED> isalso used to add multi-media or interactive behavior to HTML documentswith method 66 and system 56. The <EMBED> tag has three attributes, SRC,WIDTH, and HEIGHT, and may also contain optional parameters that can besent to a software component (e.g., a Netscape ONE plug-in) handling theembedded data type. The SRC attribute specifies the URL of the sourcedocument. The WIDTH attribute specifies the width of the embeddeddocument in pixels. The HEIGHT attribute specifies the height of theembedded document in pixels. There can also be a number of optionalparameters passed to a plug-in component with the <EMBED> tag, withPARAMETER_NAME=<PARAMETER_VALUE> (e.g., the parameters described for the<OBJECT> tag above). For more information on the <EMBED> tag, see theHTML 3, Electronic Publishing on the World Wide Web book cited above.

When the <EMBED> object tag is encountered in the document by thenetwork browser, the <EMBED> tag is parsed to pull out the <EMBED> tagattributes, and the attributes are used with method 66 and system 56 ina manner similar to that described for the <OBJECT> tag above.

The present invention is not limited to the HTML <OBJECT> and <EMBED>tags. Other HTML tags can also be used to provide method 66 and system56. In addition, the present invention is not limited to computer system10 or the browsing environment 34. The invention can also be used in aset-top box, such as those which provide interfaces to cable televisionand other television networks, in a satellite control box, such as thosewhich provide interfaces to digital and other satellite transmissionservices. The present invention may also be used in pagers, cellulartelephones, personal assistants and other wireless personalcommunications devices.

When all of the desired computer software components have been located68, downloaded 70, verified 72, installed 74, and registered 76, anyappropriate software components are returned 78 to the clientapplication (e.g., the network browser) which made the request for thecomputer software components. The software components returned to theclient application are then displayed in the document display area 52 onthe display device 20 of the local computer 36.

In an illustrative embodiment of the present invention, the networkbrowser Internet Explorer® 3.0 by Microsoft uses system 56 and method 66(and methods 80, 96 and 112) to browse HTML documents 46 on the Internet38. The software interfaces and corresponding software subroutines justdescribed for methods 66 (and methods 80, 96 and 112), and system 56 areavailable in the Internet Component Download Application ProgramInterface (API) for the Windows® 95 Operation System by MicrosoftCorporation.

HTML documents typically contain one or more HTML <OBJECT> or <EMBED>tags. When an HTML <OBJECT> or <EMBED> tag is encountered duringbrowsing, Internet Explorer® parses the appropriate parameters out ofthe <OBJECT> and <EMBED> tags and passes them to theCoGetClassObjectFromURL interface as was described above. The HTML<OBJECT> or <EMBED> tags typically point to object oriented applicationswhich provide dynamic or interactive multimedia to a HTML document.

However, other applications which are not network browsers, and do notparse HTML documents with <OBJECT> or <EMBED> tags can also use system56 and methods 66 to download any type of computer software componentfrom a local or remote computer by passing appropriate parameters toCoGetClassObjectFromURL interface. The computer software components neednot provide dynamic or interactive multimedia to a client application.In addition interfaces other than CoGetClassObjectFromURL could also beused.

It should be understood that the programs, processes, and methodsdescribed herein are not related or limited to any particular type ofcomputer apparatus, unless indicated otherwise. Various types of generalpurpose or specialized computer apparatus may be used with or performoperations in accordance with the teachings described herein.

In view of the wide variety of embodiments to which the principles ofour invention can be applied, it should be understood that theillustrated embodiments are exemplary only, and should not be taken aslimiting the scope of our invention. Rather, we claim as our inventionall such embodiments as come within the scope and spirit of thefollowing claims and equivalents thereto.

We claim:
 1. A method for automatically locating computer software from one or more remote computers, the local and remote computers being connected to a computer network, comprising: determining whether an object class identifier has been specified for a desired computer software component, and if so, using the object class identifier to locate the desired computer software component, and, if not located, choosing an appropriate object class identifier using a multipurpose Internet mail extension type associated with the desired software component to locate the desired software component, and, if not located, determining whether a uniform resource locator has been specified for a desired computer software component, and if so, using the uniform resource locator to locate the desired computer software component, and, if not located, using a pre-determined network search path to locate the desired software component.
 2. A computer-readable storage medium having stored therein instructions capable of causing a computer to perform the method of claim
 1. 3. The method of claim 1 where the determining whether an object class identifier has been specified for a desired computer software component step includes: determining whether the desired software component is installed and registered on the local computer, and is the proper version of the desired software, and, if so, locating the desired software component on the local computer.
 4. The method of claim 1 where the network search path includes a first set of uniform resource locators, a single codebase uniform resource locator, and a second set of uniform resource locators.
 5. A method for automatically locating computer software on a plurality of remote computers using a network search path, the method comprising: providing a network search path which includes a first, second and third set of uniform resource locators, where the second set of uniform resource locators includes a single codebase uniform resource locator corresponding to a predetermined application interface, and further includes one or more uniform resource locators that point to computer software components stored on remote computers connected to an intranet computer network; and searching for a desired computer software component using the first and third set of uniform resource locators and ignoring the second set of uniform resource locators, thereby preventing a search for computer software components on remote computers not connected to the intranet computer network, and, if the desired computer software component cannot be located, further searching for the desired computer software component using the second set of resource locators.
 6. A computer-readable storage medium having stored therein instructions capable of causing a computer to perform the method of claim
 5. 7. The method of claim 5 where each of the searching steps includes searching a network search path including hypertext transfer protocol servers which are used to store computer software components.
 8. The method of claim 5 where each of the searching steps include searching a network search path including servers other than hypertext transfer protocol servers used to store computer software components.
 9. The method of claim 5 where the step of searching for a desired computer software component is performed using the second set of uniform resource locators, and if the desired computer software component cannot be located, the step of further searching for the desired computer software component is performed using the first set of resource locators, and, if the desired computer software component cannot be located, the step of further searching for the desired computer software component is further performed using the third set of uniform resource locators.
 10. A computer-readable storage medium having stored therein instructions capable of causing a computer to perform the method of claim
 9. 11. A method for automatically managing computer software components obtained from one or more remote computers, the method comprising: installing computer software components obtained from the one or more of the remote computers in a permanent cache on the local computer; registering the computer software installed in the permanent cache using a predetermined portion of a registry database on the local computer; using the pre-determined portion of the registry database on the local computer to keep track of a plurality of programs executing on the local computer using the computer software components installed in the permanent cache; and using the pre-determined portion of the registry database on the local computer to automatically delete computer software components installed in the permanent cache which are no longer being used by any of the plurality of programs executing on the local computer; where automatic deletion of components is performed responsive to determining the components are no longer being used by the programs.
 12. A computer-readable storage medium having stored therein instructions capable of causing a computer to perform the method of claim
 11. 13. A method for automatically obtaining remote computer software components, the method comprising: embedding one or more reference tags in a file of data stored on a specific remote computer; parsing with an application program on the local computer the file of data stored on the specific remote computer; encountering selected ones of the embedded reference tags during the parsing of the file of data on the specific remote computer; determining whether the one or more computer software components pointed to by the encountered reference tag are already installed on the local computer, and if not, downloading, verifing, installing in a permanent cache on the local computer, registering, and displaying one of more of the computer software components on a display device on the local computer.
 14. A computer readable medium having stored therein instructions capable of causing a computer to perform the method according to claim
 13. 15. The method of claim 13 where the reference tag includes a HTML <OBJECT> tag or a HTML <EMBED> tag.
 16. The method of claim 13 where the file of data includes HTML data, Visual Basic programming language data, or Java programming language data.
 17. A method for automatically downloading and installing one or more computer software components to a local computer from one or more computers using reference tags, the computer software components including a plurality of sub-components, the reference tags used to identify the computer software components, the method comprising: receiving a request to present a document at the local computer, where the document comprises an embedded reference tag; locating automatically a control file on a specific remote computer connected to the computer network using the reference tag embedded in the document, the control file including references to one or more computer software components on the specific remote computer or one or more links to one or more computer software components on one or more of the remote computers; determining with the control file which of the plurality of sub-components for a computer software component are to be downloaded by checking version information included in the control file; downloading automatically to the local computer in an asynchronous manner each of the determined computer software sub-components; and installing automatically each of the downloaded computer software sub-components in one or more locations on the local computer.
 18. A computer readable medium having stored therein instructions capable of causing a computer to perform the method of claim
 17. 19. The method of claim 17 where the embedded reference tag includes one of the following: the HTML <OBJECT> and <EMBED> tags.
 20. A method for automatically downloading and installing computer software on a local computer from one or more remote computers, the local and remote computers being connected to a computer network, the method comprising: responsive to encountering in a document an indication that software components are specified for presentation of the document, locating automatically a control file on a specific remote computer connected to the computer network, the control file including references to one or more computer software components on the specific remote computer or one or more links to one or more computer software components on one or more other remote computers; downloading automatically to the local computer the one or more of the computer software components referenced in or linked to the control file using a uniform resource locator to locate the computer software components; verifying automatically that the computer software components downloaded to the local computer are safe to install on the local computer; installing automatically the verified computer software components in one or more locations on the local computer; and registering automatically the installed computer software components in a registry database on the local computer.
 21. A computer-readable storage medium having stored therein instructions capable of causing a computer to perform the method of claim
 20. 22. The method of claim 20 where the local computer has a central processing unit (CPU) and an operating system; and the control file includes an initialization file that includes one or more universal resource locators pointing to one or more computer software components on one or more remote computers, at least one of the computer software components being specified for the operating system or the CPU of the local computer.
 23. The method of claim 20 where the control file includes a cabinet file, the cabinet file including an initialization file, one or more software components in a compressed format, and one or more universal resource locators pointing to remote computer software components on one or more remote computers; and the initialization file includes information about the version of files needed for the software component.
 24. The method of claim 20 where the control file is a single portable executable file.
 25. The method of claim 24 where the single portable executable file is an executable application file, a dynamic link library file, and object linking and embedding control file, or an network activation control file.
 26. The method of claim 20 where the locating includes using an object class identifier, a uniform resource locator, or a network search path to locate the control file.
 27. The method of claim 20 where the verifying uses a digital signature with a digital certificate to verify the computer software components.
 28. The method of claim 20 where the registering includes registering the downloaded and verified computer software components in a module usage section of the registry database on the local computer; and the module usage section of the registry database permits tracking of usage of downloaded and installed computer software components.
 29. The method of claim 20 where the local computer has a central processing unit (CPU) and an operating system; and the locating includes using a hypertext transfer protocol server to negotiate the location of a control file including at least one computer software component specified for the CPU or the operating system of the local computer.
 30. A method for automatically locating computer software from one or more remote computers, the local and remote computers being connected to a computer network, the method comprising: determining whether an object class identifier has been specified for a desired computer software component, and if so, using the object class identifier to locate the desired computer software component and if not, determining whether a uniform resource locator has been specified for a desired computer software component, and if so, using the uniform resource locator to locate the desired computer software component, and if not, using a pre-determined network search path to locate the desired software component.
 31. A computer-readable storage medium having stored therein instructions capable of causing a computer to perform the method of claim
 30. 32. The method of claim 30 further comprising: when an object class identifier has not been specified for a desired computer software component, choosing an appropriate object class identifier using a multipurpose Internet mail extension type associated with the desired software component to locate the desired software component.
 33. The method of claim 30 where the determining whether an object class identifier has been specified for a desired computer software component step includes: determining whether the desired software component is installed and registered on the local computer, and is the proper version of the desired software, and if so, locating the desired software component on the local computer.
 34. The method of claim 30 where the network search path includes a first set of uniform resource locators, a single codebase uniform resource locator, and a second set of uniform resource locators.
 35. A method for automatically locating computer software on one or more remote computers using a network search path, the method comprising: providing a network search path which includes a first set of uniform resource locators, a second set of uniform resource locators including a single codebase uniform resource locator corresponding to a predetermined application interface, and a third set of uniform resource locators; searching for a desired computer software component using the first set of uniform resource locations, and if the desired computer software component cannot be located, searching for the desired computer software component using the second set of resource locators, and if the desired computer software component cannot be located, searching for the desired computer software component using the third set of uniform resource locators.
 36. A computer-readable storage medium having stored therein instructions capable of causing a computer to perform the method of claim
 35. 37. The method of claim 35 where the searching includes searching a network search path including hypertext transfer protocol servers which are used to store computer software components.
 38. The method of claim 35 where the searching includes searching a network search path including servers other than hypertext transfer protocol servers used to store computer software components.
 39. The method of claim 35 further comprising: providing a network search path which includes the first, second and third sets of uniform resource locators, where the second set of uniform resource locators point to computer software components stored on remote computers connected to an intranet computer network; and searching the first and third set of uniform resource locators and ignoring the second set of uniform resource locators, thereby preventing a search for computer software components on remote computers not connected to the intranet computer network.
 40. A method for automatically locating computer software on one or more remote computers using a network search path, the method comprising: providing a network search path which includes a first set of uniform resource locators, a second set of uniform resource locators including a single codebase uniform resource locator corresponding to a predetermined application interface, and a third set of uniform resource locators; searching for a desired computer software component using the second set of uniform resource locators, and if the desired computer software component cannot be located, searching for the desired computer software component using the first set of resource locators, and if the desired computer software component cannot be located, searching for the desired computer software component using the third set of uniform resource locators.
 41. A computer-readable storage medium having stored therein instructions capable of causing a computer to perform the method of claim
 40. 42. A method for automatically obtaining on a local computer a computer software component from one or more remote computers, the local computer having a central processing unit (CPU) and an operating system, where the computer software component is available in different formats for different platforms, the method comprising: requesting a desired computer software component stored on a remote computer using a specified platform-independent uniform resource locator, where the specified uniform resource locator can be used to obtain different versions of the component for different platforms; and receiving the desired computer software component in a format appropriate for the operating system or CPU of the local computer.
 43. A computer-readable storage medium having stored therein instructions capable of causing a computer to perform the method of claim
 42. 44. The method of claim 42 where the requesting includes an initialization file that includes one or more uniform resource locators pointing to one or more computer software components on one or more remote computers, at least one of the computer software components being specified for the operating system or the CPU of the local computer.
 45. The method of claim 42 where the requesting step includes using a uniform resource locator to access a hypertext transfer protocol server on a remote computer to locate the desired software component in a format specified for the operating system and CPU of the local computer.
 46. The method of claim 42 further comprising: receiving a MIME request type, where the MIME request type specifies a platform; and determining an appropriate format of the computer software component based on the specified platform.
 47. A method for automatically obtaining remote computer software components, the method comprising: embedding one or more reference tags in a file of data stored on a specific remote computer; parsing with a program on the local computer the file of data stored on the specific remote computer; encountering selected ones of the embedded reference tags during the parsing of the file of data on the specific remote computer; and determining whether the one or more computer software components pointed to by the encountered reference tag are already installed on the local computer, and if not, downloading, verifying, installing, registering, and displaying one of more of the computer software components on a display device on the local computer.
 48. A computer readable medium having stored therein instructions capable of causing a computer to perform the method according to claim
 47. 49. The method of claim 47 where the reference tag includes a HTML <OBJECT> tag or a HTML <EMBED> tag.
 50. The method of claim 47 where the file of data includes HTML data, Visual Basic programming language data, or Java programming language data.
 51. In an HTML document stored on computer-readable medium, the improvement comprising: a reference tag including one or more universal resource locators pointing to one or more computer software components on one or more remote computers, the one or more computer software components capable of being displayed on a display device on the local computer; where the computer software components provide functionality not available at the local computer; and where the reference tag is capable of being used to locate, download and install the one or more computer software components on the local computer.
 52. In an HTML document stored on computer-readable medium, the improvement comprising: a reference tag including one or more universal resource locators, pointing to one or more computer software components on one or more remote computers, at least one universal resource locator pointing to a computer software component on a local computer, the one or more computer software components capable of being displayed on a display device on the local computer; where the computer software components at the remote computers provide functionality not available at the local computer; and where the reference tag is capable of being used to locate, download and install the one or more computer software components on the local computer.
 53. A method for automatically downloading and installing computer software components from one or more computers using a HTML document being parsed on a local computer, the HTML document including one or more reference tags used to identify the computer software components, the method comprising: encountering in the HTML document one of the reference tags; responsive to encountering the reference tag in the HTML document, locating automatically a control file on a specific remote computer connected to the computer network using the reference tag, the control file including one or more computer software components on the specific remote computer or one or more links to one or more computer software components on one or more of the remote computers; downloading automatically to the local computer the one or more of the computer software components included in or linked to the control file using a uniform resource locator to locate the computer software components; installing automatically the downloaded computer software components in one or more locations on the local computer.
 54. A computer readable medium having stored therein instructions capable of causing a computer to perform the method of claim
 53. 55. The method of claim 53 further comprising: verifying automatically that the computer software components downloaded to the local computer are safe to install on the local computer; and registering automatically the installed computer software components in a registry database on the local computer.
 56. The method of claim 53 where at least one of the reference tags comprises one of the following: the HTML <OBJECT> and <EMBED> tags.
 57. A method for downloading one or more software components specified in information for presenting a document to be rendered on the local computer, the method comprising: receiving a request that the document be presented; and responsive to the request, retrieving the information for presenting the document, where the information for presenting the document comprises one or more references to the software components, where the references include a location-independent identifier; determining whether the software components are installed on the local computer via the location-independent identifier; responsive to determining the software components are not installed on the local computer, automatically downloading the software components from one or more remote locations to the local computer; and installing the software components on the local computer.
 58. The method of claim 57 where the one or more references to the software components comprise a list of one or more specified locations at which a software component to be downloaded may reside.
 59. The method of claim 58 where the automatically downloading searches the specified locations for at least one of the software components.
 60. The method of claim 58 further comprising: inhibiting searching of the specified locations to avoid downloading components from the specified locations.
 61. The method of claim 57 further comprising: presenting at least one of the installed software components in a rendered presentation of the document.
 62. The method of claim 57 where the location-independent identifier comprises an object class identifier; and the determining determines whether a component corresponding to the object class identifier is already installed on the local computer.
 63. The method of claim 57 where the document is a hypertext page and the information for presenting the document comprises HTML.
 64. The method of claim 57 where the document is presented during a first browsing session and at least one of the software components is downloaded to a permanent cache, the method further comprising: during a second browsing session, reusing the software components downloaded to the permanent cache.
 65. The method of claim 57 where the document is a first document, the method further comprising: receiving a request that the second document be presented; and responsive to the request, retrieving information for presenting the second document, where the information for presenting the second document comprises at least one reference to a software component already downloaded and installed as a result of receiving the request for the first document; determining the already-installed software components are already installed on the local computer via the location-independent identifier; and responsive to determining the already-installed software components are already installed on the local computer, presenting the second document with the already-installed software components. 